Preventing "Sick" Spaceships

May
11, 2007: Picture this: You're one of several astronauts
homeward bound after a three-year mission to Mars. Halfway
back from the Red Planet, your spacecraft starts suffering
intermittent electrical outages. So you remove a little-used
service panel to check some wiring.

To
your unbelieving eyes, floating in midair in the microgravity
near the wiring is a shivering, shimmering globule of dirty
water larger than a grapefruit. And on the wiring connectors
are unmistakable flecks of mold.

That
actually happened on the Russian space station Mir. When Mir
was launched in 1986, "it was as clean as the International
Space Station when it was launched," recounted C. Mark
Ott, health scientist at Johnson Space Center in Houston,
Texas. And the cosmonauts aboard Mir (just like the astronauts
from the U.S. and other nations aboard ISS) followed a regular
schedule of cleaning all the space station's surfaces to prevent
the growth of bacteria and molds that could jeopardize human
health.

In
the late 1990s, NASA joined the Russian space program in its
evaluation of the microbial activity aboard Mir. For planning
long-duration missions, they wanted to learn about the kinds
of organisms that can grow in spacecraft occupied for long periods
of time and where air and water are recycled. They were especially
interested because several times during its 15 years in low
Earth orbit, Mir had had the misfortune to suffer several power
outages, so the temperature and humidity rose well above normal
levels and air circulation was inadequate until the electricity
was restored.

In
1998, U.S. astronauts participating in the NASA 6 and NASA
7 visits to Mir collected environmental samples from air and
surfaces in Mir's control center, dining area, sleeping quarters,
hygiene facilities, exercise equipment, and scientific equipment.
Imagine their surprise when they opened a rarely-accessed
service panel in Mir's Kvant-2 Module and discovered a large
free-floating mass of water. "According to the astronauts'
eyewitness reports, the globule was nearly the size of a basketball,"
Ott said.

Above:
This dust mite was found floating in a globule of water onboard
Mir. Other microorganisms collected include protozoa
and amoeba. [More]

Moreover,
the mass of water was only one of several hiding behind different
panels. Scientists later concluded that the water had condensed
from humidity that accumulated over time as water droplets
coalesced in microgravity. The pattern of air currents in
Mir carried air moisture preferentially behind the panel,
where it could not readily escape or evaporate.

Nor
was the water clean: two samples were brownish and a third
was cloudy white. Behind the panels the temperature was toasty
warm—82ºF (28ºC)—just right for growing all kinds of microbeasties.
Indeed, samples extracted from the globules by syringes and
returned to Earth for analysis contained several dozen species
of bacteria and fungi, plus some protozoa, dust mites, and
possibly spirochetes.

But
wait, there's more. Aboard Mir, colonies of organisms were
also found growing on "the rubber gaskets around windows,
on the components of space suits, cable insulations and tubing,
on the insulation of copper wires, and on communications devices,"
said Andrew Steele, senior staff scientist at the Carnegie
Institution of Washington working with other investigators
at Marshall Space Flight Center.

Above:
Fungi on the ISS, growing on a panel where exercise clothes
were hung to dry. "This is a good example of how biological
contamination isn't an old problem or just specific to Mir,"
points out Mark Ott. [Larger
image]

Aside
from being unattractive or an issue for human health, microorganisms
can attack the structure of a spacecraft itself. "Microorganisms
can degrade carbon steel and even stainless steel,” Steele
continued. "In corners where two different materials
meet, they can set up a galvanic [electrical] circuit and
cause corrosion. They can produce acids that pit metal, etch
glass, and make rubber brittle. They can also foul air and
water filters."

In
short, germs can be as bad for a spacecraft's health as for
crew health.

That's
one reason that Marshall is developing the Lab-On-a-Chip Application
Development–Portable Test System, or LOCAD-PTS for short.
LOCAD-PTS is a handheld device that can diagnose the presence
of bacteria or fungi on the surfaces of a spacecraft within
minutes, far more rapidly than standard methods of culturing,
which may take several days and may require return to Earth
for further analysis.

"LOCAD-PTS
is an excellent example of the kind of hardware astronauts
will need to be autonomous in a lunar habitat or a long-duration
mission to Mars," Steele explained. "Crews must
be able to make assessments on their own. They may not be
able to get samples back to Earth." Although no electrical
or mechanical failure on Mir was specifically traced to biodegradation,
"it's not a chance you would want to take en route to
Mars."

An
early version of LOCAD-PTS, which can test for one major category
of bacteria (called Gram-negative bacteria, accounting for
about half of all bacterial species) is being tested aboard
ISS right now. New cartridges for the unit, due to be sent
up to ISS in early 2008, will be able to test for almost all
major categories of bacteria (Gram positive as well as Gram
negative) and also for fungi. Meantime, this fall (2007),
an even more advanced version—which can sense 130 specific
microorganisms, not just broad categories—Steele will test
in the Arctic.

The
ultimate plan is to develop a handheld device that can identify
thousands of individual microorganisms. "The arrays of
tests on LOCAD-PTS can be tailored to look at specific questions,"
Steele said. "For example, one array might look for genes
and chemical compounds associated with biodegradation of a
spacecraft’s structure, whereas another array might look for
human pathogens, or try to detect life on Mars."

By
getting the results of the tests in minutes, astronauts would
then know which cleaning compound would work best to prevent
a spacecraft or habitat from "falling ill."